Which product is best for cleaning tobacco / staining on interior walls

Make a cleaning solution with one gallon of hot water, three tablespoons of dish soap, and a half cup of baking soda. Use a rag to scrub the walls with this solution. If persistent, use Zinsser Cover Stain Primer Paint prior to painting.

Sugar soap. But buy the liquid one and dilute in warm water to a ratio that works. Replenishing as you go. Wipe down with clean water when removed

Sugar soap it and make sure you get every last stain out before painting or the nicotine will bleed through the paint. You could also use a shellac based paint like zinsser B.I.N expensive but it'll cover any stain ready for painting. Hope that helps

Policel basic coat for problem walls and ceilings -is good for hairline cracks and nicotine stains. Dulux has similar product witch is very good as well. ( cover some stains including nicotine.